1. Field of the Invention
The invention lies in the field of semiconductor manufacture. More particularly, the invention relates to a process for producing very thin semiconductor chips.
2. Description of the Related Art
U.S. Pat. No. 5,693,182 to Mathuni (European EP 0 729 176 A2) describes a process for producing large-scale integrated circuits on a semiconductor substrate. The substrate is a wafer which is ground thin before it is sawn up into individual chips. The damage zone on the rear side of the wafer caused by the grinding process is removed by etching. The backside of the wafer is etched prior to sawing with the front side of the wafer protected.
In the prior process, the complete wafer or silicon wafer from which the individual semiconductor chips are separated out is first of all ground thin and is then etched to the final thickness. For this purpose, the wafer is arranged with its front side (the "front side" is defined as the side carrying the circuits) on a mount substrate in order, on the one hand, to protect the circuits and, on the other hand, to provide a transport medium, since the thin wafers are very susceptible to fractures. The wafer is not separated into chips until after the etching process.
There is an increasing demand for thin semiconductor chips, since there is a demand for ever smaller installation heights. Particularly in so-called smart cards, the requirement is very strong, since the cards have a standardized thickness of only 0.8 mm, and the card manufacturers wish to make the cover of the cavity which holds the chip in the card thicker, so that it does not project visually in the card surface.
However, there is a problem with known thinning processes in that it is extremely difficult to process the thin chips any more, because they break very easily.